Interface NeighbourFinder

public interface NeighbourFinder

Used for TerrainQuad to find neighbours that are not part of the
same quad tree. Normally TerrainQuads function in a quad tree and
use the neighbour methods getRightQuad, getLeftQuad etc. to update
LOD values of the terrain (and for some other routines).
With this you can have a parent, control or spatial, that manages a group of
TerrainQuads by linking them together through these four methods.
The general orientation of TerrainQuads and their sub-quads is as such:
+-- x+ ---->
|
| 1 | 3 (quadrants)
z+ --+--
| 2 | 4
|
\/
Your implementation will still have to manage getHeight, getNormal, and
most other Terrain.java interface methods; often by offsetting the XZ
coordinate parameters.